Although there has been a strong rhetorical difference between the European Union (EU) and the United States on climate policy matters, it is really only since the mid- to late- 2000s that this difference has resulted in major differences in the range and depth of binding policies addressing climate change. Increased climate change concern in the United States in 2006–2008 created new opportunities for convergence, but failed to lead to policy change. We propose three explanations for the major differences in policy outcomes in the EU and the United States. First, distinctly different agenda-setting privileges among policy-makers in the EU and the United States caused diverse potentials for consultation and issue linkages on energy and climate policy. Second, while issue linkage helped overcome distributional obstacles in the EU, in contrast it led to more complexity and higher obstacles in the United States. Finally, legislative rules, procedures, and norms constrained the coalition-building efforts among lawmakers differently, leading to different negotiation processes and outcomes. Such differences in agenda-setting privileges, potential for issue linkage, and legislative procedures resulted in divergent climate policies in the EU and the United States that leave them wide apart in international climate negotiations.